Typically, for an off-grid or weak-grid consuming entity, e.g. a telecom facility, the main power source may include a hybrid engine-generator/battery system that can be used in backup situations. For example, if power from the commercial utility is lost, the engine-generator set can be activated to supply power to the facility. Start-up of the engine-generator set, however, takes time; therefore, the battery can provide power during this transitional time period. If the engine-generator set fails to start (e.g., runs out of fuel, suffers a mechanical failure, etc.), then the battery is able to provide power for an additional period of time. In this way, electrical energy production does not have to be drastically scaled up and down to meet momentary consumption. Rather, production can be maintained at a more constant level. Thus, electrical power systems can be more efficiently and easily operated at constant production levels.
Other battery applications may include a grid-connected energy storage system and/or motive-based storage. For example, such grid-connected battery systems can be utilized for peak shaving for commercial/industrial plants, buffering peak loads in distribution grids, energy trading, buffering solar power for night time, upgrade of solar/wind power generation, and/or any other suitable application.
Such batteries typically include a plurality of cells housed within an inner housing. Each of the cells is a sub-system building block that contains electrochemical energy stored therein in its smallest, usable form. Thus, the cells are designed to maintain reactions in separate compartments (i.e., anode and cathode) with a working membrane between them (e.g., solid electrolyte). In addition, individual cells typically have limited charge capacity (e.g., 40 A-hr) and are limited to the electrochemistry voltage potential (e.g., typically from about 1.5 V to about 3.5 V). Thus, in order to create an electrical energy storage system with useful capacity and voltage, multiple cells are connected in series, parallel or combination thereof to form a battery. Typically, a collection of cells is generally referred to as a cell pack. Thus, within the cell pack, the cells may be connected in series, parallel, and/or combinations thereof to provide a useful amount of electrical energy capacity and voltage. Accordingly, the battery or energy storage device generally refers to the complete energy storage system, including the cell pack, bus conductors, electrical insulation, thermal insulation, temperature regulation-subsystem, electronic control sub-system, and/or external handling features.
In the battery applications described above, as well as any other suitable battery applications, it is important to maintain a uniform temperature between the cells inside the battery. For modern designs, the cooling hardware flows air underneath the cell pack and then over the top. However, since the airflow is not sealed, some of the air flows over the front cells, thereby causing the front cells to cool more than the remaining cells. When the cells get colder, their internal electrical resistances increase, which can drive a higher voltage across the cells during recharge at a fixed current flow. This higher voltage can then damage the cold cells, which can degrade the performance and/or reliability of the overall battery.
Thus, it would be advantageous to provide an improved energy storage system having reduced temperature variability between cells.